1. Field of the Invention
The present invention relates to a cap device and an inkjet printer.
2. Description of the Related Art
Conventionally, inkjet printers for performing printing by an inkjet method are known. Such an inkjet printer, for example, performs printing on a recording paper sheet supplied by a paper feeding device. The inkjet printer includes a carriage having an ink head unit mounted thereon. The carriage moves above the recording paper sheet in a width direction of the recording paper sheet. (In this specification, the width direction of a medium such as a recording paper sheet or the like will be referred to as a “main scanning direction”. A direction perpendicular to the main scanning direction will be referred to as a “sub scanning direction”.) The inkjet printer, for example, has an overall operation thereof controlled by a microcomputer.
As shown in, for example, FIGS. 11a and 11b, in such an inkjet printer, a carriage 100 movable in the main scanning direction may have a plurality of ink head units 101 mounted thereon. Provision of the plurality of ink head units 101 shortens the time required for printing. Each of the ink head units 101 has a plurality of inkjet nozzles (not shown) formed on a bottom surface thereof. The inkjet nozzles are each an ejection orifice for ejecting ink to a medium such as a recording paper sheet or the like. The ink head units 101 are located above the medium during printing, and are located at a wait position after, for example, the printing on the medium is finished.
The inkjet printer includes a cap device for capping the bottom surfaces of the ink head units 101 at the wait position. The cap device is located below the ink head units 101 at the wait position.
Such a cap device includes a cap formed of a flexible material such as rubber or the like. The cap is closely contactable with a bottom surface of an ink head unit having inkjet nozzles formed thereon. The cap protects the bottom surface of the ink head unit. Since the bottom surface of the ink head unit is protected by the cap, the inkjet nozzles is protected against dust or the like. The cap device has an element for discharging thickened ink or air bubbles in the ink from the inkjet nozzles. This prevents clogging of the inkjet nozzles and incorporation of air bubbles into the ink in the inkjet nozzles.
When the ink head unit is moved to the wait position at a prescribed timing, for example, after the finish of the printing, the cap in the cap device is raised to closely contact the bottom surface of the ink head unit. In this state, the cap forms a hermetically closed space around the inkjet nozzles of the ink head unit. After this, a suction device connected to the cap device sucks the air in the hermetically closed space. As a result, the pressure in the hermetically closed space becomes a negative pressure, and thus the ink and the air bubbles are discharged from the inkjet nozzles.
In order to perform the above-described operation properly, the cap device needs to be positioned accurately with respect to the ink head unit which is at the wait position. When the ink head unit is located at the wait position, the cap and the bottom surface of the ink head unit need to closely contact each other to form a hermetically closed space around the inkjet nozzles. In the case where a plurality of ink head units are mounted on the carriage, caps are located in positional correspondence with the ink head units, respectively. Namely, the caps are located so as to form hermetically closed spaces around the inkjet nozzles in the ink head units, respectively.
Conventionally, a cap device including a plurality of caps is designed and produced as follows. First, the position of, for example, a leftmost ink head unit, among the plurality of ink head units mounted on the carriage, is determined. Next, the positions of the other ink head units are determined based on the position of the leftmost ink head unit. In the meantime, the positions of the plurality of caps on a base member, which is a base portion of the cap device, are determined. First, the position of a leftmost cap is determined. Next, the positions of the other caps are determined based on the position of the leftmost cap. Then, the position of the cap device with respect to the carriage is determined. More specifically, the position of the cap device is determined such that when the carriage is at the wait position, the leftmost cap is located in positional correspondence with the leftmost ink head unit.
During the production of an inkjet printer, the ink head units are located on the carriage, at the positions determined as described. The caps are located on the base member of the cap device, at the positions determined as described above. The cap device is located at the position determined as described above.
However, this technique causes the following situation. When, for example, the size of components or the like is varied, an error occurs to the positions of the caps other than the cap used as the reference, with respect to the ink head units other than the ink head unit used as the reference. In the above-described example, an error occurs to the positions of the caps other than the leftmost cap, with respect to the ink head units other than the ink head unit corresponding to the leftmost cap.
Therefore, the positions of the caps need to be adjusted when the cap device is assembled, which has been pointed out as a problem. A known technique for solving this problem is disclosed in, for example, Japanese Laid-Open Patent Publication No. 2000-255075.
Japanese Laid-Open Patent Publication No. 2000-255075 discloses a cap unit slidable in the sub scanning direction with respect to a cap unit mounting section and a guide claw located away from the cap unit by a prescribed distance in the sub scanning direction. Japanese Laid-Open Patent Publication No. 2000-255075 describes that even when the cap unit is positionally diverged in the sub scanning direction with respect to a recording head, the cap unit is guided by the guide claw in the sub scanning direction while being raised, and thus the position of the cap unit in the sub scanning direction with respect to the recording head can be corrected.
However, the technique described in Japanese Laid-Open Patent Publication No. 2000-255075 merely corrects the position of the cap unit in the sub scanning direction with respect to the recording head, but cannot correct the position of the cap unit in the main scanning direction Y with respect to the recording head. Therefore, the cap unit cannot be always put into close contact with an appropriate position in the recording head. For example, there are cases where the cap unit cannot form a hermetically closed space around the recording head nozzle.
For this reason, even the cap device including such a position adjusting mechanism disclosed in Japanese Laid-Open Patent Publication No. 2000-255075 does not sufficiently function in an inkjet printer including a plurality of ink head units, and has been pointed out as having problems such as clogging of the inkjet nozzles and incorporation of air bubbles.
In such a situation, a cap device which includes a plurality of caps for performing capping for a plurality of ink head units, and is capable of correcting the position of at least one cap in the main scanning direction, is strongly desired. An inkjet printer including such a cap device is also desired.